In recent years, against the existing standard television system such as the NTSC system or the PAL system, etc., which handles images (pictorial images) of aspect ratio of 4:3, new television systems to handle images (pictorial images) of the wide aspect ratio of 16:9, such as, for example, EDTV (Extended Definition Television) system have been proposed, and video equipments adapted for handling images of plural aspect ratios are being put into practical use.
The applicant of this application has already proposed, as disclosed in, e.g., the Japanese Patent Application Laid Open No. 316284/1992 publication, a video camera apparatus in which an aspect ratio converting circuit for converting a digital picture signal of the wide aspect ratio of 16:9 into a digital picture signal of the aspect ratio of 4:3 is provided, thereby making it possible to cope with both the standard television system and the television system of the wide aspect ratio. In the above-mentioned aspect ratio converting circuit, a digital picture signal of the wide aspect ratio of 16:9 is converted into a digital picture signal of the aspect ratio of 4:3 by the time axis expansion of 4/3 times at the H period.
Meanwhile, when the digital picture signal of the aspect ratio of 4:3 is generated from the digital picture signal of the wide aspect ratio of 16:9 by the time axis expansion processing of 4/3 times, the sampling frequency f.sub.s2 of the digital picture signal of the aspect ratio of 4:3 would become f.sub.s2 =(3/4)f.sub.s1 with respect to the sampling frequency f.sub.s1 of the digital picture signal of the wide aspect ratio of 16:9. Accordingly, the video camera apparatus provided with the aspect ratio converting circuit is required to handle digital picture signals of two kinds of sampling frequencies f.sub.s1, f.sub.s2 in the digital signal processing system such as .gamma. correction, etc. of the succeeding stage. For this reason, signal processing systems of two systems must be used with respect to two kinds of sampling frequencies f.sub.s1, f.sub.s2, or respective circuits must be caused to cope with both sampling frequencies f.sub.s1, f.sub.s2. This leads to complicated circuit and increase in the circuit scale, etc.
Moreover, if an approach is employed to carry out the aspect ratio conversion of color image by luminance/color difference system such as Y, U, V or Y, I, Q, etc., in the case where the Spatial Offset Method is employed in the imaging (image pick-up) system so that high resolution is provided, since the sampling frequency of the luminance signal Y is twice greater than that of the three prime color system of R, G, B by reflection of the Spatial Offset effect, high speed data processing is required. As a result, realization thereof is difficult.
Further, in the case where the aspect ratio conversion is carried out by the composite signal, when time axis conversion processing is implemented to the composite signal, the frequency of sub-carrier would be changed. As a result, it becomes impossible to use it as the composite signal. For this reason, the time or labor for decoding in advance and/or post encoding which are to be to be required not only becomes wasteful, but also injures the picture quality.
In view of actual circumstances as described above, an object of this invention is to provide a digital video camera apparatus capable of generating, from an analog image pick-up signal having a first aspect ratio obtained by imaging means, an output digital picture signal of a first sampling rate having a second aspect ratio different from the first aspect ratio to output it.
Another object of this invention is to provide a digital video camera apparatus having a function to carry out aspect ratio conversion of color image.
A further object of this invention is to provide a digital video camera apparatus having a function to carry out aspect ratio conversion with respect to three prime color signals obtained by imaging means employing the Spatial Offset Method.
A further object of this invention is to provide an aspect ratio converting apparatus capable of generating, from an input digital picture signal of a first sampling rate indicating an image of a first aspect ratio, an output digital picture signal of a first sampling rate indicating an image of a second aspect ratio.
A further object of this invention is to provide an aspect ratio converting apparatus capable of carrying out aspect ratio conversion of color image.
A further object of this invention is to provide an aspect ratio converting apparatus capable of carrying out aspect ratio conversion with respect to three prime color digital picture signals obtained by respectively digitizing, by a first sampling rate, three prime color signals obtained by imaging means employing the Spatial Offset Method.
A further object of this invention is to provide an aspect ratio converting apparatus capable of carrying out aspect ratio conversion by a single clock.